That is an Incentive Spirometer... after any surgery a patient should be using it. When you are under during surgery, the sacs in the lower part of your lungs will slightly collapse. Commonly given to patients in a hospital after surgery, this device will help prevent an onset of pneumonia. This device makes you take slow deep breaths to help the sacs be able to completely inflate. It should be used 5-10x every 2 hours for a day or two after surgery.